1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for allocating resources in a wireless communication system.
2. Related Art
The institute of electrical and electronics engineers (IEEE) 802.16e standard was adopted in 2007 as a sixth standard for international mobile telecommunication (IMT)-2000 in the name of ‘WMAN-OFDMA TDD’ by the ITU-radio communication sector (ITU-R) which is one of sectors of the international telecommunication union (ITU). An IMT-advanced system has been prepared by the ITU-R as a next generation (i.e., 4th generation) mobile communication standard following the IMT-2000. It was determined by the IEEE 802.16 working group (WG) to conduct the 802.16m project for the purpose of creating an amendment standard of the existing IEEE 802.16e as a standard for the IMT-advanced system. As can be seen in the purpose above, the 802.16m standard has two aspects, that is, continuity from the past (i.e., the amendment of the existing 802.16e standard) and continuity to the future (i.e., the standard for the next generation IMT-advanced system). Therefore, the 802.16m standard needs to satisfy all requirements for the IMT-advanced system while maintaining compatibility with a mobile WiMAX system conforming to the 802.16e standard.
A user equipment may request radio resources for transmitting uplink data or control signal. This may be called a bandwidth request (BR) process. The user equipment transmits a BR header to a base station through a UL resource allocated by the base station to request a bandwidth.
A hybrid automatic repeat request (HARQ) may be used even for the BR header. That is, when the base station successfully receives the BR header transmitted by the user equipment, the base station transmits an acknowledgement (ACK) for the BR header to the user equipment to notify that the base station successfully receives the BR header. When the base station does not successfully receive the BR header transmitted by the user equipment, the base station transmits a non-acknowledgement (NACK) for the BR header to the user equipment to notify that the base station does not successfully receive the BR header. The user equipment that receives the NACK may retransmit the BR header to the base station. The HARQ may be divided into an adaptive HARQ and a non-adaptive HARQ.
When the BR header is retransmitted according to the HARQ, a method for efficiently allocating the UL resource for the BR header is required.